Successive Convexification for Trajectory Optimization with Continuous-Time Constraint Satisfaction

Fuente: arXiv
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Main Authors: Elango, Purnanand, Luo, Dayou, Kamath, Abhinav G., Uzun, Samet, Kim, Taewan, Açıkmeşe, Behçet
Format: Preprint
Published: 2024
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author Elango, Purnanand
Luo, Dayou
Kamath, Abhinav G.
Uzun, Samet
Kim, Taewan
Açıkmeşe, Behçet
author_facet Elango, Purnanand
Luo, Dayou
Kamath, Abhinav G.
Uzun, Samet
Kim, Taewan
Açıkmeşe, Behçet
contents We present successive convexification, a real-time-capable solution method for nonconvex trajectory optimization, with continuous-time constraint satisfaction and guaranteed convergence, that only requires first-order information. The proposed framework combines several key methods to solve a large class of nonlinear optimal control problems: (i) exterior penalty-based reformulation of the path constraints; (ii) generalized time-dilation; (iii) multiple-shooting discretization; (iv) $\ell_1$ exact penalization of the nonconvex constraints; and (v) the prox-linear method, a sequential convex programming (SCP) algorithm for convex-composite minimization. The reformulation of the path constraints enables continuous-time constraint satisfaction even on sparse discretization grids and obviates the need for mesh refinement heuristics. Through the prox-linear method, we guarantee convergence of the solution method to stationary points of the penalized problem and guarantee that the converged solutions that are feasible with respect to the discretized and control-parameterized optimal control problem are also Karush-Kuhn-Tucker (KKT) points. Furthermore, we highlight the specialization of this property to global minimizers of convex optimal control problems, wherein the reformulated path constraints cannot be represented by canonical cones, i.e., in the form required by existing convex optimization solvers. In addition to theoretical analysis, we demonstrate the effectiveness and real-time capability of the proposed framework with numerical examples based on popular optimal control applications: dynamic obstacle avoidance and rocket landing.
format Preprint
id arxiv_https___arxiv_org_abs_2404_16826
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Successive Convexification for Trajectory Optimization with Continuous-Time Constraint Satisfaction
Elango, Purnanand
Luo, Dayou
Kamath, Abhinav G.
Uzun, Samet
Kim, Taewan
Açıkmeşe, Behçet
Optimization and Control
We present successive convexification, a real-time-capable solution method for nonconvex trajectory optimization, with continuous-time constraint satisfaction and guaranteed convergence, that only requires first-order information. The proposed framework combines several key methods to solve a large class of nonlinear optimal control problems: (i) exterior penalty-based reformulation of the path constraints; (ii) generalized time-dilation; (iii) multiple-shooting discretization; (iv) $\ell_1$ exact penalization of the nonconvex constraints; and (v) the prox-linear method, a sequential convex programming (SCP) algorithm for convex-composite minimization. The reformulation of the path constraints enables continuous-time constraint satisfaction even on sparse discretization grids and obviates the need for mesh refinement heuristics. Through the prox-linear method, we guarantee convergence of the solution method to stationary points of the penalized problem and guarantee that the converged solutions that are feasible with respect to the discretized and control-parameterized optimal control problem are also Karush-Kuhn-Tucker (KKT) points. Furthermore, we highlight the specialization of this property to global minimizers of convex optimal control problems, wherein the reformulated path constraints cannot be represented by canonical cones, i.e., in the form required by existing convex optimization solvers. In addition to theoretical analysis, we demonstrate the effectiveness and real-time capability of the proposed framework with numerical examples based on popular optimal control applications: dynamic obstacle avoidance and rocket landing.
title Successive Convexification for Trajectory Optimization with Continuous-Time Constraint Satisfaction
topic Optimization and Control
url https://arxiv.org/abs/2404.16826